"Unwanted freshwater pests such as didymo, lake snow [and lagarosiphon] pose a serious threat to our rivers, streams and lakes. "We are asking people moving between waterways to check, clean, dry any equipment that has come into contact with river or lake water. Some freshwater pests, like didymo, are microscopic and can be spread by a single drop of water. The long-running "check, clean, dry'' programme implemented by the council has been reported as having helped slow the spread of water pests. Lake snow is found in Lakes Wanaka, Hawea, Wakatipu and Moke Lake.

Source: Otago Daily Times January 14, 2018 19:52 UTC